The info below comes from an E3 2013 interview with Gamespot. It is assumed information from this interview alone as well as confirming that older characters do indeed work in SWAP Force as the official site notes in their FAQ.

Skylanders collectors probably won’t have any issue with picking up new SWAP Force figures when they are released October 13th, however if you’re a bit tight on funds you’ll be happy to learn that one aspect of the game seems to support your current set.Read More